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Black dual wall adhesive-lined heat shrink tubing

3/8" Dual Wall Heat Shrink Black

STH38B-4

$3.99

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3/8" dual wall heat shrink tubing in black, with an adhesive lining. It has a 3:1 shrink ratio, so it recovers to about one-third of its supplied 3/8" diameter, and the adhesive melts as it shrinks to seal out water, salt and road spray. Rated -45°C to 125°C; begins shrinking at 100°C.

Use it for: 8–6 AWG power wire, ring terminal barrels and small bundles on boats, trailers, trucks and anywhere a connection sees water.

Getting the right size: it fits 12–6 AWG of our GPT primary wire and battery cable (wire or terminal OD 0.125"–0.312"). Not sure? See the heat shrink tubing size chart. Other black sizes: 1/4" · 1/2" · 3/4" · 1" · 1-1/2". Same size in red. For dry locations where you don't need a seal, 3/8" single wall costs less.

Sold in 6 in and 4 ft pieces. See all dual wall heat shrink.

• Diameter: 3/8" (before shrinking)
• Wire Gauge Range: 12-6 AWG (our GPT primary wire / battery cable; fits 0.125"–0.312" OD)
• Shrink Ratio: 3:1 (shrinks to 1/3 original diameter)
• Material: Dual-wall polyolefin with adhesive lining
• Temperature Rating: -45°C to 125°C (-49°F to 257°F)
• Activation Temperature: 100°C (212°F) - begins shrinking
• Waterproof: Yes (when properly heated)

• Marine Wire Splicing & Connections - Seal wire splices, terminal connections, and cable joints in boats where saltwater exposure requires waterproof protection that prevents corrosion and electrical failure.

• Outdoor Electrical Installations - Protect wire connections in landscape lighting, outdoor outlets, and weatherproof junction boxes where rain, snow, and UV exposure demand durable, waterproof insulation.

• Automotive & Trailer Wiring - Insulate battery cable connections, wire splices, and terminal ends in vehicles and trailers where road spray, moisture, and vibration require sealed protection against corrosion.

• Underground Cable Protection - Seal direct burial splices, well pump connections, and irrigation system wiring where moisture, soil chemicals, and pressure require permanent waterproof barriers.

  • UL Listed
  • CSA Certified
  • Meets Mil-Spec 23053/4 standards
  • Free Shipping on orders $50+
  • Orders placed before 3pm PST ship same day
  • 30-day no-hassle return
  • Buyer may be liable for return shipping charges

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